This application proposes a prospective longitudinal examination of the effects of psychosocial factors on a comprehensive measure of treatment outcome in a sample of female Roux-en-Y gastric bypass (RYGB) patients. The focal psychosocial variables are post-operative behavioral adherence to dietary and exercise prescriptions, depressive symptoms and binge eating. Although post-surgical diet and exercise prescriptions are thought to facilitate weight loss and support long-term health outcomes, there is a dearth of research examining the impact of non-adherence on treatment outcome. Further, depression and binge eating, which are prevalent among the treatment seeking obese, are putative correlates of behavioral non-adherence. The specific aims of the present proposal integrate several objectives of 2 key priority areas outlined in Healthy People 2000: physical fitness (priority area 1) and nutrition (priority area 2). Specifically, research that informs the optimization of bariatric surgery outcomes addresses the objectives of increasing sound weight loss practices and decreasing the prevalence of overweight. Treatment outcome will be defined in terms of surgical success, using the multi-dimensional Bariatric Analysis and Reporting Outcome System (BAROS;Oria &Morehead, 1998). Assessments will take place at two time points: baseline (3 months pre-operative) and 1-year post-surgery. Baseline and 1-year assessments will consist of self-report questionnaires, structured and semi-structured interviews, and clinician rated sections of the BAROS. The proposed examination of psychosocial correlates of behavioral non-adherence and the impact of these variables on surgical outcome represents a novel contribution to the literature. The findings promise to improve the understanding of how behavioral adherence impacts weight change, quality of life, and psychological well-being after gastro-intestinal bypass surgery. It will elucidate the psychosocial factors that may hinder or promote post-operative adherence. Ultimately, this research may provide surgeons with the means to identify those patients who are most likely to benefit from surgery and those who may be at higher risk for poor outcomes. Findings will also inform behavioral interventions designed to optimize post-surgical outcome.